A plurality pixel unit is formed in the panel of the thin film transistor liquid crystal display, and each pixel unit has a red, green and blue sub-pixel. The luminance of the sub-pixel is determined by the gamma reference voltage. The function of the generating circuit of gamma reference voltage is to determine the gamma reference voltage by the request of the gamma curve of the liquid crystal display and to be a reference voltage of the grayscale display of the thin film transistor liquid crystal display. Each of the gamma reference voltage is input to the source driving device of the thin film transistor liquid crystal display, by the calculation by the digital to analog converter in the source driving device, to generate all of the grayscale voltage.
In the process of the gamma reference voltage transmitting from the gamma reference voltage circuit to the thin film transistor liquid crystal display, the ripple will easily occur by the interference and makes the distortion of the gamma reference voltage. In order to solve the question above, a LC filter circuit is formed between the gamma reference voltage circuit and the thin film transistor liquid crystal display to filter the gamma reference voltage in the conventional technology. But since the characteristic of each of the pixel unit is different, the capacitance characteristic of each of the pixel unit is different. So the filter effect of the gamma reference voltage is influenced. If the filter effect of the gamma reference voltage is enough, the voltage difference is unstable in the two terminals of the liquid crystal, causing the instability of the reversing angle of the liquid crystal to produce flicker phenomenon, affecting the display quality.